Answer:
The answer is number two extinction happened, this was the time dinosaurs went extinct ebcause lack of sun because oh how much dirt was blown into the earth atmosphere becuase of the asteriod, third option is talking about big bang theroy so that dosnt apply!
Explanation:
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No, because there is only so much food for them to eat.
The same applies for all levels of the food chain.
I think the answer is liver and hepatic portal vein
Hope this helps